1. Field of the Invention
This invention relates to musical apparatus. In particular, the invent ion pertains to an automatic composer which automatically composes melody.
2. Description of the Prior Art
Several automatic composers are known which automatically compose a melody. Examples are disclosed in U.S. Pat. Nos. 4,399,731, 4,664,010, WO No. 86/05619 and Japanese Patent application laid-open SHO62-187876.
The automatic composer of U.S. Pat. No. 4,399,731 uses trial-and-error method which generates random numbers to compose a melody note pitch succession. Thus, the composer has an infinite space of melody composing but lacks knowledge or art of music composition so that the chance of getting a good melody is too low.
Each automatic composer of U.S. Pat. No. 4,664,010 and WO No. 86/05619 is a melody composer or transformer which transforms a given melody. The melody transformation involves a mathematical operation (mirror transformation of a pitch succession, linear transformation of a two dimensional space of pitch and durational series). With a limited space of the transformation, the composer has only a fixed and mathematical (rather than musical) capability of melody composition.
Japanese patent application laid-open SHO 62-187876 discloses a melody composer which utilizes a Markov chain model to generate a pitch succession. The apparatus composes a melody based on a pitch transition table indicative of a Markov chain of a pitch succession. The composed melody has a musical style of the pitch transition table. While it can compose a musical melody at a relatively high efficiency, the composer provides a small space of melody composition since the composed melody style is limited.
Common disadvantages of the prior art described above are
(1) no capability of analyzing or evaluating a melody,
(2) no use of melody analyzed results for melody composition and thus
(3) low capability of composing a musical melody.
In view of these, the present inventor proposed an automatic composer which utilizes a melody analyzing and evaluating capability for melody composition, as disclosed in U.S. Pat. No. 4,926,737 and U.S. Pat. No. 5,099,740 (divided from U.S. Pat. No. 4,926,737). The automatic composer has a stored knowledge-base of melody which classifies nonharmonic tones by their relationship formed with harmonic tones based on the premise that a melody is a mixed succession of harmonic and nonharmonic tones. The stored knowledge-base of nonharmonic tone classification is used to analyze a melody (motive) supplied by a user. It is also used to compose or synthesize a melody. The melody composition involves two steps. The first step generates a harmonic tone succession or arpeggio by embodying an arpeggio featuring pattern (developed from the motive) according to a musical progression (a chord in progression). The second step generates nonharmonic tones and places them in the harmonic tone succession. Nonharmonic tones are generated by embodying a nonharmonic tone featuring pattern developed from the motive according to a musical progression (a scale in progression) and the stored knowledge of nonharmonic tone classification. Whereas it can compose a musical melody reflecting a feature of the motive, the automatic composer has the following disadvantages.
(a) The preprocess to the melody composition involving analyzing a motive and creating an idea (arpeggio and nonharmonic tone featuring patterns) of a melody to be composed requires a considerable amount of data processing.
(b) The double-step melody composing is different from a human process of composing a melody. Thus, the automatic composer fails to realize a faithful Artificial Intelligence of musical composition.
(c) It is difficult to compose a melody in real time due to the preprocess and the double-step melody composing. In fact, the automatic composer is designed to compose a melody in non-real time on a measure by measure basis. After completing melody composition, the apparatus plays the composed melody by a tone generator. Should a melody idea (arpeggio and nonharmonic tone featuring pattern) be given in advance, a real-time melody composition would still be unfeasible. This is because the tasks of realizing the melody idea (double-step melody composing) are concentrated at a particular time such as a bar line time. This would result in a lag of the automatic performance (e.g., delay of a melody tone sounding) when the (computer) tasks are concentrated.
(d) A chord progression must be supplied from an input device to the automatic composer. This is not easy for those users having no or little knowledge of music.
(e) The automatic composer must be supplied with a motif and a chord progression which should be an fundamental part of the musical composition.
It is, therefore, desired that an automatic composer can:
(A) compose a musical melody in a single step, and
(B) compose and play a melody in real time.
The automatic composer of U.S. Pat. Nos. 4,926,737 and 5,099,740 also discloses a rhythm generator which generates a rhythm of a melody by modifying an original rhythm (motive rhythm). The rhythm modification involves inserting and/or deleting note-on timings into or from the original rhythm according to rhythm control data called pulse scale having weights for individual timings in a musical time interval such as a measure.
The rhythm generator has a limited capability of generating rhythm patterns. It is difficult to generate those rhythm patterns which have the same tone number but are different in a subtle way from each other.